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 193   <div class="section" id="appending-or-prepending-to-data-on-the-server">
 194 <h1>Appending or Prepending to data on the server<a class="headerlink" href="#appending-or-prepending-to-data-on-the-server" title="Permalink to this headline">¶</a></h1>
 195 <p id="index-0">Appending or Prepending to data on the server</p>
 196 <div class="section" id="synopsis">
 197 <h2>SYNOPSIS<a class="headerlink" href="#synopsis" title="Permalink to this headline">¶</a></h2>
 198 <p>#include &lt;libmemcached/memcached.h&gt;</p>
 199 <dl class="function">
 200 <dt id="_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t">
 201 <span id="_CPPv317memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv217memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_prepend__memcached_stP.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_prepend</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 202 <dd></dd></dl>
 203
 204 <dl class="function">
 205 <dt id="_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t">
 206 <span id="_CPPv316memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv216memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_append__memcached_stP.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_append</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 207 <dd></dd></dl>
 208
 209 <dl class="function">
 210 <dt id="_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t">
 211 <span id="_CPPv324memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv224memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_prepend_by_key__memcached_stP.cCP.s.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_prepend_by_key</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>group_key</em>, size_t <em>group_key_length</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 212 <dd></dd></dl>
 213
 214 <dl class="function">
 215 <dt id="_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t">
 216 <span id="_CPPv323memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="_CPPv223memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t"></span><span id="memcached_append_by_key__memcached_stP.cCP.s.cCP.s.cCP.s.time_t.uint32_t"></span><a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t">memcached_return_t</a> <code class="sig-name descname">memcached_append_by_key</code><span class="sig-paren">(</span><a class="reference internal" href="memcached_create.html#_CPPv412memcached_st" title="memcached_st">memcached_st</a> *<em>ptr</em>, <em class="property">const</em> char *<em>group_key</em>, size_t <em>group_key_length</em>, <em class="property">const</em> char *<em>key</em>, size_t <em>key_length</em>, <em class="property">const</em> char *<em>value</em>, size_t <em>value_length</em>, time_t <em>expiration</em>, uint32_t <em>flags</em><span class="sig-paren">)</span><a class="headerlink" href="#_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="Permalink to this definition">¶</a><br /></dt>
 217 <dd></dd></dl>
 218
 219 <p>Compile and link with -lmemcached</p>
 220 </div>
 221 <div class="section" id="description">
 222 <h2>DESCRIPTION<a class="headerlink" href="#description" title="Permalink to this headline">¶</a></h2>
 223 <p><a class="reference internal" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_prepend()</span></code></a> and memcached_append are used to
 224 modify information on a server. All methods take a key, and its length to
 225 store the object. Keys are currently limited to 250 characters when using
 226 either a version of memcached which is 1.4 or below, or when using the text
 227 protocol. You must supply both a value and a length. Optionally you
 228 may test an expiration time for the object and a 16 byte value (it is
 229 meant to be used as a bitmap). “flags” is a 4byte space that is stored
 230 alongside of the main value. Many sub libraries make use of this field,
 231 so in most cases users should avoid making use of it.</p>
 232 <p><a class="reference internal" href="#_CPPv417memcached_prependP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_prepend()</span></code></a> places a segment of data before the last piece
 233 of data stored. Currently expiration and key are not used in the server.</p>
 234 <p><a class="reference internal" href="#_CPPv416memcached_appendP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_append"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_append()</span></code></a> places a segment of data at the end of the last
 235 piece of data stored. Currently expiration and key are not used in the server.</p>
 236 <p><a class="reference internal" href="#_CPPv424memcached_prepend_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_prepend_by_key"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_prepend_by_key()</span></code></a> and
 237 <a class="reference internal" href="#_CPPv423memcached_append_by_keyP12memcached_stPKc6size_tPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_append_by_key"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_append_by_key()</span></code></a> methods both behave in a similar
 238 method as the non key methods. The difference is that they use their
 239 group_key parameter to map objects to particular servers.</p>
 240 <p>If you are looking for performance, <a class="reference internal" href="memcached_set.html#_CPPv413memcached_setP12memcached_stPKc6size_tPKc6size_t6time_t8uint32_t" title="memcached_set"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_set()</span></code></a> with non-blocking
 241 IO is the fastest way to store data on the server.</p>
 242 <p>All of the above functions are tested with the
 243 <a class="reference internal" href="memcached_behavior.html#_CPPv4N20memcached_behavior_t26MEMCACHED_BEHAVIOR_USE_UDPE" title="MEMCACHED_BEHAVIOR_USE_UDP"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_BEHAVIOR_USE_UDP</span></code></a> behavior enabled. However, when using
 244 these operations with this behavior on, there are limits to the size of the
 245 payload being sent to the server.  The reason for these limits is that the
 246 Memcached Server does not allow multi-datagram requests
 247 and the current server implementation sets a datagram size to 1400 bytes. Due
 248 to protocol overhead, the actual limit of the user supplied data is less than
 249 1400 bytes and depends on the protocol in use as, well as the operation being
 250 executed. When running with the binary protocol,
 251 <a class="reference internal" href="memcached_behavior.html#_CPPv4N20memcached_behavior_t34MEMCACHED_BEHAVIOR_BINARY_PROTOCOLE" title="MEMCACHED_BEHAVIOR_BINARY_PROTOCOL"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_BEHAVIOR_BINARY_PROTOCOL</span></code></a>, the size of the key,value,
 252 flags and expiry combined may not exceed 1368 bytes. When running with the
 253 ASCII protocol, the exact limit fluctuates depending on which function is
 254 being executed and whether the function is a cas operation or not. For
 255 non-cas ASCII set operations, there are at least 1335 bytes available
 256 to split among the key, key_prefix, and value; for cas ASCII operations
 257 there are at least 1318 bytes available to split among the key, key_prefix
 258 and value. If the total size of the command, including overhead, exceeds
 259 1400 bytes, a <a class="reference internal" href="memcached_return_t.html#_CPPv4N18memcached_return_t23MEMCACHED_WRITE_FAILUREE" title="MEMCACHED_WRITE_FAILURE"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_WRITE_FAILURE</span></code></a> will be returned.</p>
 260 </div>
 261 <div class="section" id="return">
 262 <h2>RETURN<a class="headerlink" href="#return" title="Permalink to this headline">¶</a></h2>
 263 <p>All methods return a value of type <a class="reference internal" href="memcached_return_t.html#_CPPv418memcached_return_t" title="memcached_return_t"><code class="xref cpp cpp-type docutils literal notranslate"><span class="pre">memcached_return_t</span></code></a>.
 264 On success the value will be <a class="reference internal" href="memcached_return_t.html#_CPPv4N18memcached_return_t17MEMCACHED_SUCCESSE" title="MEMCACHED_SUCCESS"><code class="xref cpp cpp-any docutils literal notranslate"><span class="pre">MEMCACHED_SUCCESS</span></code></a>.
 265 Use <a class="reference internal" href="memcached_strerror.html#_CPPv418memcached_strerrorP12memcached_st18memcached_return_t" title="memcached_strerror"><code class="xref cpp cpp-func docutils literal notranslate"><span class="pre">memcached_strerror()</span></code></a> to translate this value to a printable
 266 string.</p>
 267 </div>
 268 <div class="section" id="see-also">
 269 <h2>SEE ALSO<a class="headerlink" href="#see-also" title="Permalink to this headline">¶</a></h2>
 270 <p><em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man1/memcached.1.html">memcached(1)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/libmemcached.3.html">libmemcached(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_strerror.3.html">memcached_strerror(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_set.3.html">memcached_set(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_add.3.html">memcached_add(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_cas.3.html">memcached_cas(3)</a></em> <em class="manpage"><a class="manpage reference external" href="http://man7.org/linux/man-pages/man3/memcached_replace.3.html">memcached_replace(3)</a></em></p>
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